Funding is requested to support our ongoing studies toward identification of molecular mechanisms mediating effects of acetylcholine (ACh), its pharmacologic congeners and tobacco products on oral keratinocytes (OKC). The continuous cycle of keratinocyte birth and death is a self-sustained process controlled, in part, by the local hormone ACh through the signaling pathways that couple each type of ACh receptors to regulation of a particular cell function. Free cytotransmitter ACh is present in physiologically-relevant concentrations in the epithelium lining the upper digestive tract. OKC express both the ACh synthesizing and degrading enzymes, and both nicotinic and muscarinic classes of ACh receptors. A novel paradigm of cell regulation via nicotinic ACh receptors (nAChRs) has been discovered in studies of the cholinergic proteins termed SLURP (secreted mammalian Ly-6/urokinase plasminogen activator receptor-related protein)-1 and -2. Preliminary results indicate that SLURP-1 and -2 regulate keratinocyte proliferation, apoptosis and differentiation. Most importantly, SLURPs and professional nicotinic antagonists can abolish, in part, the abilities of the nicotinederived nitrosamines 4-(methylnitrosamino)-1-(3?pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) to cause transformation of immortalized OKC. We will test the following working hypotheses: 1) the pathobiologic effect of NNK is mediated predominantly via alpha7 and/or alpha9 nAChR(s), and that of NNN?via alpha3-made nAChR(s);2) SLURP proteins can prevent nitrosamine-dependent transformation of oral cells both in vivo and in vitro, and abolish tobacco/nicotine-dependent alterations in the keratinocyte cell cycle, growth and differentiation;and 3) SLURP-1 competes mainly with NNK for binding to the homopentameric nAChR(s) and SLURP-2?with NNN at the binding site of heteropentameric nAChR(s), and both SLURPs interfere with the nitrosamine-induced nAChR signaling.
The Specific Aims will be to determine: 1) the role of keratinocyte nAChRs in mediating the pathobiologic effects of tobacco nitrosamines;2) the roles for SLURP-1 and -2 in the physiologic protection of OKC from tobacco toxicity;and 3) the receptor-mediated signaling mechanisms mediating SLURP-1 and -2 actions on OKC.
The primary significance of the application lies in its goal to elucidate how nicotinic acetylcholine receptors mediate pathobiologic effects of tobacco-derived nitrosamines and how SLURP can prevent the toxic effects of nitrosamines. Integrating structural and functional information about SLURPs and the epithelial acetylcholine axis will facilitate a better understanding of normal development and function of the epithelium lining the upper digestive tract. Learning the pharmacology of the SLURP vs. nitrosamine action on oral keratinocytes will help develop an effective prevention programs wherein hazardous effects of tobacco products are anticipated, or even abolished, by a pharmacologic ligand of a specific nicotinic acetylcholine receptors acting as an antidote.
|Gordon, William; Galitovskiy, Valentin; Edwards, Robert et al. (2013) The tobacco carcinogen nitrosamine induces a differential gene expression response in tumour susceptible A/J and resistant C3H mouse lungs. Eur J Cancer 49:725-33|
|Grando, Sergei A (2012) Muscarinic receptor agonists and antagonists: effects on keratinocyte functions. Handb Exp Pharmacol :429-50|
|Galitovskiy, Valentin; Chernyavsky, Alexander I; Edwards, Robert A et al. (2012) Muscle sarcomas and alopecia in A/J mice chronically treated with nicotine. Life Sci 91:1109-12|
|Chernyavsky, Alexander I; Kalantari-Dehaghi, Mina; Phillips, Courtney et al. (2012) Novel cholinergic peptides SLURP-1 and -2 regulate epithelialization of cutaneous and oral wounds. Wound Repair Regen 20:103-13|
|Chikova, Anna; Grando, Sergei A (2011) Naturally occurring variants of human ?9 nicotinic receptor differentially affect bronchial cell proliferation and transformation. PLoS One 6:e27978|
|Chernyavsky, Alexander I; Arredondo, Juan; Skok, Maryna et al. (2010) Auto/paracrine control of inflammatory cytokines by acetylcholine in macrophage-like U937 cells through nicotinic receptors. Int Immunopharmacol 10:308-15|
|Chernyavsky, Alexander I; Arredondo, Juan; Galitovskiy, Valentin et al. (2010) Upregulation of nuclear factor-kappaB expression by SLURP-1 is mediated by alpha7-nicotinic acetylcholine receptor and involves both ionic events and activation of protein kinases. Am J Physiol Cell Physiol 299:C903-11|
|Chernyavsky, A I; Arredondo, J; Galitovskiy, V et al. (2009) Structure and function of the nicotinic arm of acetylcholine regulatory axis in human leukemic T cells. Int J Immunopathol Pharmacol 22:461-72|
|Chernyavsky, Alexander I; Arredondo, Juan; Qian, Jing et al. (2009) Coupling of ionic events to protein kinase signaling cascades upon activation of alpha7 nicotinic receptor: cooperative regulation of alpha2-integrin expression and Rho kinase activity. J Biol Chem 284:22140-8|
|Arredondo, Juan; Chernyavsky, Alexander I; Jolkovsky, David L et al. (2008) Receptor-mediated tobacco toxicity: acceleration of sequential expression of alpha5 and alpha7 nicotinic receptor subunits in oral keratinocytes exposed to cigarette smoke. FASEB J 22:1356-68|
Showing the most recent 10 out of 29 publications